The present invention generally relates to a system, method and computer instructions for x-ray imaging. More particularly, the present invention relates to a system method and computer instructions for x-ray imaging that allow an x-ray image created using a square x-ray detector to be readily rotated without losing portions of the radiated anatomy from the x-ray image.
X-rays are electromagnetic waves of short wavelength that are capable of penetrating some thickness of matter. Certain matter attenuates x-rays more than other types of matter. For example, x-rays directed at a body, such as a human body, are attenuated somewhat by body tissue, such as skin and muscle, more so by internal organs, such as lungs, and even more so by bones. Thus, by detecting x-rays that have passed through a body, an image of the internal structures of the body can be created.
Traditional x-ray imaging is comparable to a snapshot taken with an ordinary camera. A single, still image is created using film. Traditional x-ray imaging may be used for diagnostic purposes, such as diagnosing a broken bone, for example.
Another type of x-ray imaging called “fluoroscopy” is more like recording with a video camera. A continuous, possibly changing, image is created and displayed by continually detecting a stream of x-rays. Fluoroscopy may allow a physician to study moving body structures while performing surgery in an operating room, for example.
X-rays may be emitted from an x-ray source as an x-ray stream. Radiation absorbent material, such as lead or tungsten, may be used in devices that define the shape and size of an x-ray stream. One device that defines the shape and size of an x-ray stream is a collimator. A collimator may define the shape and size of an x-ray stream so that the stream is a circle or a square of a certain size, for example.
As mentioned above, an x-ray stream may be directed through a body to create an image of the internal structures of the body. The area of the body that the x-ray stream passes through may be referred to as “radiated anatomy” or the “exposed area” of the body. In order to detect x-rays after they have passed through a body, an x-ray detector may be situated such that the x-ray stream contacts the x-ray detector after it passes through the body. Further, an x-ray image may be created and/or displayed based on the x-rays that contact the x-ray detector.
Although x-rays may be useful in medicine, x-rays are also a type of radiation. Radiation may be harmful in certain doses. Thus, it is desirable to limit exposure to x-rays when possible.
In order to comply with United States Food and Drug Administration regulations, an x-ray detector should detect all x-rays that pass through a body, allowing for an image to be displayed that shows the entire radiated anatomy of the body. See 21 C.F.R. §1020.32. Further, in certain situations, an image that results from passing x-rays through a body may need to be rotated so that the image is presented in a certain orientation. Thus, x-ray imaging systems should meet two requirements: (1) an image of the entire “radiated anatomy” of a body should be detected and displayed; and (2) x-ray images should be readily rotated.
Circular collimators and corresponding circular x-ray detectors were once the norm in fluoroscopic x-ray imaging. Circular x-ray detectors utilized image intensifiers and image capture devices, such as cameras, to create and subsequently display x-ray images. When an x-ray image needed to be rotated, the device that captured the image was simply rotated. Because the collimator and the x-ray detector were both circular, and the image capture device created a circular image, the entire radiated anatomy could be shown in the image and the image could be rotated for display at any orientation.
Flat panel x-ray detectors have been developed. Flat panel x-ray detectors are advantageous because they create higher quality images than their round predecessors. The higher quality is due in part to integration of an image capture device into the detector, rather than utilizing an image intensifier and a camera.
However, flat panel detectors are not readily rotatable. This creates difficulty because the device that creates the image is no longer readily rotatable. Further, flat panel detectors are usually square in shape. This creates difficulty because, even if the detector was readily rotatable, rotating the detector may cause x-rays that have passed through certain radiated anatomy not to contact the detector, resulting in the creation of images that do not show all of the radiated anatomy.
Thus, there is a need for a system, method and computer instructions for x-ray imaging that allow an x-ray image created using a square x-ray detector to be readily rotated without losing portions of the radiated anatomy from the x-ray image.